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Aqa biology unit 1 tuesday january 2011 official paper

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Reply 20

343arcou

Original post by affleming

i got the same, but more of like a complex chemistry way figuring out moles and all that

Haha I was about to till I realised I multiply 20 by 0.2 the subtract that answer from twenty for the other one :smile:

Reply 21

343arcou

Anyone know the answers to 1A and 1B?

Reply 22

swiftylol

Original post by Robert McGeachan

Anyone know the answers to 1A and 1B?

http://www.thestudentroom.co.uk/showthread.php?t=1515442 for the answers

(edited 13 years ago)

Reply 23

mkb230

1(a) Cell surface membrane / Plasma membrane (1)
1(b) Ribosomes if 80s; (1)
Golgi apparatus; (1)
Mitochrondria; (1)
ER; (1)
Nuclues; (1)
etc, difference between eukaryotic and prokaryotic accepted (2 MAX)
1(ci) Higher magnification (1)
1(cii) Specimen can be seen a 3d image (1) Reject: Specimens don’t have to be thin / is not dead
1(D) 0.43 – 0.45 (2)
1(e) As height above sea level increases, the deaths from cholera decreases; (exponentially) (1)
Steep decrease, then constant decrease (1)

2(ai) Substrate binds to enzyme, causing it to change shape; (1)
active site changes shape so that ezyme can fit; (1) (2 MAX)
this causes enzyme to enter transition state (1)
2(aii) The induced fit model explains why the enzyme enters a transition state
2(b) Binds to active site / Competes with substrate; (1)
Similar shape to substrate; (1)
Prevents enzyme substrate complex; (1)

3(a) (i) G. (1)
3(aii) E (1)
3(b) Pressure in ventricles greater than in arteries (1)
3(c) Allows blood from the atria to pass into the ventricles / So that the atria can empty / finish contracting; (1)
Before the ventricles contract (1)
3(di) 90.9 / 91 (2)
5000/55 Allow one mark if wrong answer but correct calculation
3(dii) Unknown (Please contribute) (2)

4(a) Double Bond; (1)
In R-Group (1)

4(b) No, there is only a correlation, no causation; (1)
Other factor could cause decrease in risk of CHD; (1)
Sample size unknown; (1)
4(c) Glycosidic (1) Reject : ESTER
4(cii) Contains 3 fatty acid molecules / Contains a glycerol molecule (1)
4(ciii) 9 (1)

5(a) Sodium chloride on surface could affect the results; (1)
Unknown, Please contribute; (1)
5(b) Unknown, Please contribute. (1)
5(c) Enables comparison; (1)
Cylinders have different starting masses (1)
5(d) Improves reliability; (1)
Enables a mean to be calculated (1) (2 MAX)
Enables outliers to be identified (1) Accept: Anomaly
5(e)0.34 – 0.36 (1)

6(a)UNKNOWN, PLEASE CONTRIBUTE! (1)
6(b) other types of virus contain different antigen; (1)
No memory/plasma cells created (for other viruses) (1)
6(c) Unknown, please contribute (2)
6(d) Cancer takes a long time to develop (1)
Unknown, please contribute (1)
6(e) Unknown, please contribute (1)
6(f) little chance of the micro-organism finding a suitable host (1)
Disease is maintained at a low level in population (1)

7a -
droplet. bacteria attaches to mucus/water(1)
bacteria increases in alveoli (1)
immune response to release white blood cells (1)
causes an inflamation and lymph nodes are enlarged (1)
you cough up blood because of the scar tissue made (1)
7b.
loss of elasticity/permenantely stretched (1) Accept: Infected milk
fresh oxygen cannot pass by into the alveoli/ or blood. (1)
small surface area/ reduced alveoli (1)
less oxygen will pass by into the alveoli/ less gets into the blood/ heart has to work harder (1)
cannot respire/ no energy (1)
N.B concentration gradient points are valid too.

Predicted Grade boundary:

A: 39
B: 34
C: 29
D: 24
E: 19
U: Anything below 19

Disclaimer: This may not be 100% accurate, please contribute if there are any mistakes / inaccuracy's

Warning: DO NOT rely on these for your results, as they may prove to be incorrect.

Reply 24

Rosiegsm

Original post by mkb230

2(b) Binds to active site / Competes with substrate; (1)
Similar shape to substrate; (1)
Prevents enzyme substrate complex; (1)

Surely it would have been a non-competitive inhibitor, because the question asked how the thing stopped he bacteria producting folic acid. A competitive inhibitor would slow the production down, but wouldn't stop it completely like a non-competitive inhibitor would.

Also, the chain coming off the molecule was different so there wouldn't fit?

Reply 25

mkb230

Original post by Rosiegsm

Yes I know but the question was very poorly worded so I think as long as you mention either inhibitors, you should get the marks. I don't how many people noticed this but as a Chemist I was absolutely disgusted to see that they had drawn the benzene molecule wrong.

Reply 26

sarang187

4 ciii) Did everyone get 9? :s

Reply 27

sarang187

did everyone get 9 for 4ciii

Reply 28

lupon7

Original post by Rosiegsm

Was 2b about non-competitive inhibitors or competitive inhibitors?

I'm not sure, I put non-competitive because in the question is says that the drug prevented the formation of folic acid but the shape of the enzyme looked similar as it had a benzene ring and an NH2 at the bottom but the top group was different. Competitive inhibitors don't prevent folic acid being formed they just slow down the rate at which it is formed, non-competitve does. I'm not too sure though :P lousy question!!

Reply 29

M | k e

Original post by mkb230

If I remember from the exam wasn't it an amine group attached to a cyclo hexene? I don't think it was supposed to be benzene lol :tongue:

. Or it could of been the Kekule structure of benzene? They know this is the wrong structure but it is still commonly used & accepted to represent benzene.

As for whether it was competitive/non-competitive I admit I was caught in 2 minds in the exam, but only one part of the molecule binds to the enzyme and as they showed the structures of the 2 molecules, and both of them so similar with different "R" groups this suggested to me they were looking for competitive otherwise this would be a really strange thing to put in purely to confuse people. But I agree the wording "prevents" definitely indicates non-competitive which is where I was a little confused :tongue:

(edited 13 years ago)

Reply 30

mkb230

Original post by M | k e

If I remember from the exam wasn't it an amine group attached to a cyclo hexene? I don't think it was supposed to be benzene lol :tongue:

.

As for whether it was competitive/non-competitive I admit I was caught in 2 minds in the exam, but only one part of the molecule binds to the enzyme and as they showed the structures of the 2 molecules, and both of them so similar with different "R" groups this suggested to me they were looking for competitive otherwise this would be a really strange thing to put in purely to confuse people. But I agree the wording "prevents" definitely indicates non-competitive which is where I was a little confused :tongue:

I am pretty sure that the name of the compound was PABA and it was meant to be a benzene ring with an amine group attached to it. Anyway there were lots of other mistakes on the paper. They completely messed up the units for the cardiac output question.

Reply 31

M | k e

Original post by mkb230

Perhaps you're right can't say I really take notice of those things when I'm in an exam.

Also to clear up the competitive/non-competitive stuff: http://www.associatedcontent.com/article/1831623/antimetabolites_inhibition_by_sulfanilamide.html

States that the process is one of competitive inhibition. So I guess that is what they were looking for (phew) however I also wouldn't be surprised if they allowed either method of inhibition because of how it was worded.

Reply 32

TanishaBellum

Do you have this and the mark scheme for the AQA BIOLOGY UNIT 2 Exam that took place today? 13th Jan 2011.

Thanks!

Reply 33

SaraElen17

6(a)UNKNOWN, PLEASE CONTRIBUTE! (1)
6(b) other types of virus contain different antigen; (1)
No memory/plasma cells created (for other viruses) (1)
6(c) Unknown, please contribute (2)
6(d) Cancer takes a long time to develop (1)
Unknown, please contribute (1)
6(e) Unknown, please contribute (1)
6(f) little chance of the micro-organism finding a suitable host (1)
Disease is maintained at a low level in population (1)

In 6a I put that girls ages 12-13 are not usually sexually active so will be most affective in this age group.
For 6c to try to increase amount of memory cells produced, and so more anti-bodies get secreted into the blood stream (humoral response).
For 6e people will still be given smear tests as they could have a different form of the HPV virus not 16 + 18. The vaccinations are only for 16 + 18 so women still need to go for smear tests. :smile:

Hope this helps with the gaps.

Reply 34

lemar

5(a) Sodium chloride on surface could affect the results; (1)
Unknown, Please contribute; (1)
5(b) Unknown, Please contribute. (1)
5(c) Enables comparison; (1)
Cylinders have different starting masses (1)
5(d) Improves reliability; (1)
Enables a mean to be calculated (1) (2 MAX)
Enables outliers to be identified (1) Accept: Anomaly
5(e)0.34 – 0.36 (1)

what if i said to check if their is any mistakes being made do you think it is a mark

for 5 d

Has anyone done the ISA for unit 1 Biology yet?
I have to do it tomorrow and it would help if any1 has any info on what the experiment is about and the questions in the written paper?

Reply 37

lemar

R group is only in proteins i swear

Reply 38

Mina!SS

Hey,, for he difference between prokaryotes and eukaryotes, I think I put Mitochondria and microvilli, coz it said 'in the small intestine',, is that right?